In the audio technology research field, an audio quality test is important. For example, in a wireless communications scenario, during transmission from a calling party to a called party, a sound needs to undergo various processing, such as analogy-to-digital (A/D) conversion, encoding, transmission, decoding, and digital-to-analog D/A conversion. In this process, quality of a received speech signal may deteriorate because of a factor such as a packet loss appearing during the encoding or transmission. A phenomenon of speech quality deterioration is referred to as speech distortion. Many methods for testing speech quality have been studied in the industry. For example, a manual subjective test method in which a test assessment result is given by organizing testers to listen to to-be-tested audio. However, the method has a long period and high costs. A method for automatically detecting in a timely manner whether speech distortion occurs needs to be obtained in the industry, so as to automatically test and assess the speech quality.